Effects of canopy closure on photosynthetic characteristics of Ilex latifolia Thunb. in Phyllostachys pubescens forests

Abstract

Plantation under the forest is a good way of agroforestry, but the canopy closure has a great influence on understory herbs’ growth. In the study, different canopy closures of Phyllostachys pubescens forests were set up to explore its influence on the growth of Ilex latifolia Thunb. The photosynthetic characteristics of Ilex latifolia leaves under different canopy closures were determined by Li-6400 portable photosynthetic system. The results showed that the net photosynthetic rate curve of Ilex latifolia leaves of T1 (canopy closure of 0.56) was bimodal with an obvious "midday depression" phenomenon, while the net photosynthetic rate curves of T2 (canopy closure of 0.72) and T3 (canopy closure of 0.86) were unimodal. The results of light response curve showed that the photosynthetically active radiation and transpiration rate reduced with the increasing of canopy closures. The photosynthetically active radiation, transpiration rate, stomatal conductance, and net photosynthetic rate of Ilex latifolia leaves of T2 were higher than those of T3. Although the net photosynthetic rate of T2 was lower than that of T1, it had no obvious photo-inhibition which affected plant growth. Overall, the canopy closure of 0.72 was more suitable for the growth of Ilex latifolia. The herb plantation in the bamboo forest should be considered with the canopy closure for a better growth.